Field of the Invention
Embodiments of the invention relate to surgical implant devices for repairing angular bone deformities, in particular, metatarsus primus adductus. While certain embodiments of the invention were conceived for the purposes of correcting metatarsus primus adductus, it is conceivable that other embodiments can be adapted to correct other bone deformities as long as there is a stable bone somewhat adjacent to an unstable bone.
Description of the Related Art
Metatarsus primus adductus is a progressive angular deformity in the foot, between the first and second metatarsals, when the unstable or hypermobile first metatarsal deviates medially, increasing the intermetatarsal angle between the first and second metatarsals Surgical procedures to correct this condition are chosen based on the severity of the angular deformity. Traditionally, surgical correction of moderate to severe angular deformities between the first and second metatarsals involves bone remodeling, osteotomies, wedge resection of bone or joint fusions, which cause irreversible alterations to bone and joint structures. A more desirable technique is to anatomically correct the deformity by reducing the abnormally wide angle between the two metatarsals by tethering them closer together using suture like material. Known are U.S. Pat. Nos. 8,221,455, 7,901,431, 7,875,058, 5,529,075, and U.S. Patent Application No. 2011/0224729.
U.S. Pat. Nos. 8,221,455, 7,901,431, 7,875,058 and U.S. Patent Application No. 2011/0224729 are tethering techniques whereby fiberwire, a suture-like material, along with buttress plates and/or buttons are used to tether the first and second metatarsals closer together like a tightrope. These techniques require holes to be drilled through both the first and second metatarsals. The Mini Tightrope system by Arthrex is an example of the tethering technique. First, a hole is drilled through the first and second metatarsals. Next, a buttress plate is secured to the second metatarsal bone by passing the suture through holes in the plate and through holes in both bones, then reducing the angular deformity by tightening the suture using a button and suture knot located on the medial side of the first metatarsal. The Mini Tightrope FT system by Arthrex is another example of tethering technique which uses an anchor-suture-button complex, where a threaded anchor is drilled into the second metatarsal base and the suture thread is then passed through a hole in the first metatarsal and the angular deformity is reduced as the suture thread is tightened and secured with a suture knot and button located along the medial aspect of the first metatarsal. Both of these tethering techniques require drilling into both the second and first metatarsals. U.S. Pat. No. 5,529,075 is similar in that it too requires drilling through the first and second metatarsals. Instead of a flexible suture-anchor technique, this reference requires the installation of a rigid stabilizing member between the first and second metatarsal. However, each of these references suffers from one or more of the following disadvantages: a hole must be drilled into or through the second metatarsal, to secure one end of the tethering device while the other (medial) end of the tethering device is secured with a button.
Drilling a hole through the second metatarsal, which is significantly smaller in diameter by comparison to the first metatarsal, severely weakens the bone. To minimize weakening of the second metatarsal, the hole must be drilled through the centerline of the bone so that a maximum amount of bone remains above and below the hole. Nevertheless, drilling a hole through the centerline of the second metatarsal is especially difficult because it is done at an angle through a hole in the first metatarsal. Making the procedure more difficult, the drilling must be done with little or no visibility. A second metatarsal bone which has been drilled through is more vulnerable to stress and/or fracture from tension caused by the tethering techniques. Fracture of the second metatarsal is a common and potentially devastating complication of these tethering techniques. Additionally, the use of buttons and suture knots located along the medial aspect of the first metatarsal can cause irritation of tissue, knot loosening and skin irritation/breakdown from prominent components.
Some surgeons have attempted to avoid drilling into the second metatarsal via a modification of the tethering technique, known as lasso technique. With the lasso technique, no holes are drilled through the second metatarsal, and no buttress plate or button is used. Instead, suture tape (i.e. Fibertape) is tied around the second metatarsal in the form of a cow-hitch knot and then secured to the first metatarsal. While the lasso technique avoids drilling through the second metatarsal by instead looping suture tape around the metatarsal, the suture tie itself can cause periosteal reaction and bone callus formation in some patients due to friction between the suture tape and the bone. To avoid periosteal reaction, few surgeons use absorbable suture to tether the first and second metatarsals together, but once the suture finally absorbs there is likely some loss of correction and possible recurrence of angular deformity.
Because of the aforementioned problems, there is a need for method and device for reducing angular bone deformities between two bones, using a tethering technique with a suture material which not only avoids the complications associated with drilling into the second metatarsal, but also avoids the friction and tension forces (i.e. rope-burn) associated with lasso-type techniques and which also avoids the complications associated with the prominent medial button and suture knot.